Go 1.22 in the image; on start, backend/rudder-engine/setup-runtime.sh fetches its pinned runtime and
model (SHA-256 checked, skipped when present) into RUDDER_HOME (default /data/rudder, meant for the
persistent volume) and builds the engine; RUDDER_AUDIO=browser. The pull loop rebuilds the untracked
engine binary when backend/rudder-engine changes. /api/rudder stays behind the sign-in: it is served
by Vite on the gated / route, and the only public routes remain /cdn/ and /api-prod/api/. README:
the flag, and 3.5 GB with it on.